The authors discussed the use of ion chromatography to measure formate and acetate ion collect in rain water in the state of Zulia, Venezuela. Their work was published in Journal of Chromatography, 671 (1994) 193-196. Based on this study the authors reported that acid concentration in rain was much lower in La Esperanza than other Venezuela’s sites.
1. Introduction:
Formic acid and acetic acids have been identified as biogenic emissions from different vegetative source. US Environmental Protection Agency has recommended using ion chromatography (IC) to detect and measure the amount of organic and inorganic acids in environmental samples. This instrument, IC, can provide accurate and reliable result in samples including rain samples.
2. Experimental
2.1 Sampling
A series of polyethylene bottles were used to collect 41 rain samples over one year in La Esperanza region. The sample bottles were cooled to 4 oC and were cleaned carefully with Milli Q water to avoid any contamination.
2.2 Reagents
A series of stock standard solution of sodium formate and sodium acetate were prepared from the corresponding salts. A 100 mM solution of these standards were prepared and chloroform was used as a preservative.
2.3 Equipment and operating conditions
All analysis were performed by using an IC instrument from Dionex Model QIC which had an APM analytical pump, HPIC-AS4 separator, AMMS suppressor columns, a conductivity detector and a [[#|data processing system]].
The sample was injected directly into eluent pathway and different anions were separated and detected based on their pKa and type of eluent and resin type. A conductivity detector was used to detect different anions eluting from the specific column.
3. Results and discussion
3.1. Qualitative and quantitative analysis
This specific technique did not differentiate between undissociated and dissociated organic acids. Other measurements such as total concentration, pH, pKa values for the acids are known and were utilized to calculate amounts of undissociated and dissociated acids. The common acids have reported in rain water are formic, acetic, propionic, lactic, and pyruvid acids.
Most samples contain much larger concentration of formic and acetic acid than other impurities such as propionic, lactic, and pyruvic acids. A 0.5 to 80 u M concentration of different acids were used to calibrate IC and this method provided an excellent correlation coefficient. The analysis of all samples also provide excellent result with an acceptable standard of deviation.
3.2 . Organic acid concentrations
Based on these tests the authors proposed that the amount of formic and acetic acid at La Experanza location were lower than the other rural Venezuelan sites. At this specific site, La Experanza, the highest amount of acids was detected at the beginning of season and it was dropped as the season ends. In addition to formic and acetic acids the authors reported higher concentration of sulfuric acid due to human activities. This increase in sulfuric acid was not reported for in eastern Venezuelan’s region.
4. Acknowledgements
The work presented in this paper was supported by the Council for Human and Scientific Development ( CONDES) of the University of Zulia.
(1) MORALES, J.; DEMEDINA, H.; DENAVA, M.; VELASQUEZ, H.; SANTANA, M. Determination of Organic-Acids by Ion Chromatography in Rain Water in the State of Zulia, Venezuela. Journal of Chromatography a1994, 671, 193-196.DOI
Determination of organic acid by ion chromatography in rain water in the State of Zulia, Venezuela
Jose' A. Morales, Hilda L.de Medina, Marlene G.de Nava, Harvi Velasquez, Magaly SantanaThe authors discussed the use of ion chromatography to measure formate and acetate ion collect in rain water in the state of Zulia, Venezuela. Their work was published in Journal of Chromatography, 671 (1994) 193-196. Based on this study the authors reported that acid concentration in rain was much lower in La Esperanza than other Venezuela’s sites.
1. Introduction:
Formic acid and acetic acids have been identified as biogenic emissions from different vegetative source. US Environmental Protection Agency has recommended using ion chromatography (IC) to detect and measure the amount of organic and inorganic acids in environmental samples. This instrument, IC, can provide accurate and reliable result in samples including rain samples.
2. Experimental
2.1 Sampling
A series of polyethylene bottles were used to collect 41 rain samples over one year in La Esperanza region. The sample bottles were cooled to 4 oC and were cleaned carefully with Milli Q water to avoid any contamination.
2.2 Reagents
A series of stock standard solution of sodium formate and sodium acetate were prepared from the corresponding salts. A 100 mM solution of these standards were prepared and chloroform was used as a preservative.
2.3 Equipment and operating conditions
All analysis were performed by using an IC instrument from Dionex Model QIC which had an APM analytical pump, HPIC-AS4 separator, AMMS suppressor columns, a conductivity detector and a [[#|data processing system]].
The sample was injected directly into eluent pathway and different anions were separated and detected based on their pKa and type of eluent and resin type. A conductivity detector was used to detect different anions eluting from the specific column.
3. Results and discussion
3.1. Qualitative and quantitative analysis
This specific technique did not differentiate between undissociated and dissociated organic acids. Other measurements such as total concentration, pH, pKa values for the acids are known and were utilized to calculate amounts of undissociated and dissociated acids. The common acids have reported in rain water are formic, acetic, propionic, lactic, and pyruvid acids.
Most samples contain much larger concentration of formic and acetic acid than other impurities such as propionic, lactic, and pyruvic acids. A 0.5 to 80 u M concentration of different acids were used to calibrate IC and this method provided an excellent correlation coefficient. The analysis of all samples also provide excellent result with an acceptable standard of deviation.
3.2 . Organic acid concentrations
Based on these tests the authors proposed that the amount of formic and acetic acid at La Experanza location were lower than the other rural Venezuelan sites. At this specific site, La Experanza, the highest amount of acids was detected at the beginning of season and it was dropped as the season ends. In addition to formic and acetic acids the authors reported higher concentration of sulfuric acid due to human activities. This increase in sulfuric acid was not reported for in eastern Venezuelan’s region.
4. Acknowledgements
The work presented in this paper was supported by the Council for Human and Scientific Development ( CONDES) of the University of Zulia.
(1) MORALES, J.; DEMEDINA, H.; DENAVA, M.; VELASQUEZ, H.; SANTANA, M. Determination of Organic-Acids by Ion Chromatography in Rain Water in the State of Zulia, Venezuela. Journal of Chromatography a 1994, 671, 193-196.DOI
Ion chromatography system using electrochemical suppression and detector ..
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